Filename: 102-drop-opt.txt
Title: Dropping "opt" from the directory format
Author: Nick Mathewson
Created: Jan 2007
Status: Closed
Implemented-In: 0.2.0.x
Overview:
This document proposes a change in the format used to transmit router and
directory information.
This proposal has been accepted, implemented, and merged into dir-spec.txt.
Proposal:
The "opt" keyword in Tor's directory formats was originally intended to
mean, "it is okay to ignore this entry if you don't understand it"; the
default behavior has been "discard a routerdesc if it contains entries you
don't recognize."
But so far, every new flag we have added has been marked 'opt'. It would
probably make sense to change the default behavior to "ignore unrecognized
fields", and add the statement that clients SHOULD ignore fields they don't
recognize. As a meta-principle, we should say that clients and servers
MUST NOT have to understand new fields in order to use directory documents
correctly.
Of course, this will make it impossible to say, "The format has changed a
lot; discard this quietly if you don't understand it." We could do that by
adding a version field.
Status:
* We stopped requiring it as of 0.1.2.5-alpha. We'll stop generating it
once earlier formats are obsolete.